Around 120 CF patients in Ireland are set to benefit from the drug, which will cost the state in excess of €20m per annum.

An assessment by the National Centre for Pharmacoeconomics (NCPE) in January 2013 confirmed the benefits of the drug included significant improvements in lung function, increased body weight, improvement in patients’ quality of life and a 55 percent reduction in pulmonary exacerbations.

Minister for Health James Reilly said the terms of the deal with with Kalydeco's manufacturer, Vertex Pharmaceuticals, will remain confidential, reports RTE.

He said: “I had a phone call with the Taoiseach this morning to discuss this, I also discussed it with (Minister of State) Kathleen Lynch and we are absolutely clear that this drug must be made available to the 120 people who have that genome type and can benefit from it."